Fortran90 comparing real values

Question

I have to following subroutine:

SUBROUTINE matprod(nkval, matrix, tkval, field)
 implicit none

 integer, allocatable, intent(in) :: matrix(:,:,:)
 real, allocatable, intent(inout) :: tkval(:,:,:)
 real, allocatable, intent(in) :: nkval(:,:)
 integer, intent(in) ::field
 integer :: temp, i, j

 allocate(tkval(field,size(matrix,dim=1),3))
 temp=size(matrix,dim=1)

 do i=1,field
   do j=1,temp
     tkval(i,j,:)=matmul(matrix(j,:,:),nkval(:,i))
     if (tkval(i,j,1).eq.-0.5) then
       tkval(i,j,1)=0.5
     endif
     if (tkval(i,j,2).eq.-0.5) then
       tkval(i,j,2)=0.5
     endif
     if (tkval(i,j,3).eq.-0.5) then
       tkval(i,j,3)=0.5
     endif
   enddo
 enddo

END SUBROUTINE matprod

Where afer matrix multiplication i have a set of 3d points, which i know for a fact contain '-0.5' and i want to catch those and turn them into positive 0.5. For some reason, my if statements don't see those. Why?

here is the output sample of "tkval" with the J counter displayed:

   1
  0.2500000      0.7499999      0.7499999
       2
  0.2500000      0.7499999      0.7499999
       3
  0.7499999      0.2500000      0.7499999
       4
  0.7499999      0.7499999      0.2500000
       5
  0.7499999      0.2500000      0.7499999
       6
  0.7499999      0.7499999      0.2500000
       7
 -0.5000000      0.0000000     -0.7499999
       8
 -0.5000000     -0.7499999      0.0000000
       9
  0.0000000     -0.5000000     -0.7499999
      10
  0.0000000     -0.7499999     -0.5000000
      11
 -0.5000000      0.0000000     -0.7499999
      12
 -0.5000000     -0.7499999      0.0000000
      13
  0.5000000      0.5000000     -0.2500000
      14
  0.5000000     -0.2500000      0.5000000
      15
  0.0000000     -0.5000000     -0.7499999
      16
  0.0000000     -0.7499999     -0.5000000
      17
  0.5000000      0.5000000     -0.2500000
      18
  0.5000000     -0.2500000      0.5000000

Answer 1

So this is one way that i thought of to solve my problem:

 if ((tkval(i,j,1).lt.-0.49999).and.(tkval(i,j,1).gt.-0.50001)) then
       tkval(i,j,1)=tkval(i,j,1)*(-1)
     endif
     if ((tkval(i,j,2).lt.-0.49999).and.(tkval(i,j,2).gt.-0.50001)) then
       tkval(i,j,2)=tkval(i,j,2)*(-1)
     endif
     if ((tkval(i,j,3).lt.-0.49999).and.(tkval(i,j,3).gt.-0.50001)) then
       tkval(i,j,3)=tkval(i,j,3)*(-1)